INVESTIGADORES
CALVO Ernesto Julio
artículos
Título:
Donnan permselectivity in layer-by-layer self-assembled redox polyelectrolyte thin films
Autor/es:
ERNESTO JULIO CALVO; A. WOLOSIUK,
Revista:
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
Referencias:
Año: 2002 p. 8490 - 8490
ISSN:
0002-7863
Resumen:
Redox polyelectrolyte multilayers have been assembled with use of the layer-by-layer (LBL)
deposition technique with cationic poly(allylamine) modified with Os(bpy)2ClPyCHO (PAH-Os) and anionic
poly(styrene)sulfonate (PSS) or poly(vinyl)sulfonate (PVS). Different behavior has been observed in the
formal redox potential of the Os(II)/Os(III) couple in the polymer film with cyclic voltammetry depending on
the charge of the outermost layer and the electrolyte concentration and pH. The electrochemical quartz
crystal microbalance (EQCM) has been used to monitor the exchange of ions and solvent with the external
electrolyte during redox switching. At low ionic strength Donnan permselectivity of anions or cations is
apparent and the nature of the ion exclusion from the film is determined by the charge of the topmost layer
and solution pH. At high electrolyte concentration Donnan breakdown is observed and the osmium redox
potential approaches the value for the redox couple in solution. Exchange of anions and water with the
external electrolyte under permselective conditions and salt and water under Donnan breakdown have
been observed upon oxidation of the film at low pH for the PAH-Os terminating layer. Moreover, at high pH
values and with PVS as the terminating layer EQCM mass measurements have shown that cation release
was masked by water exchange.2ClPyCHO (PAH-Os) and anionic
poly(styrene)sulfonate (PSS) or poly(vinyl)sulfonate (PVS). Different behavior has been observed in the
formal redox potential of the Os(II)/Os(III) couple in the polymer film with cyclic voltammetry depending on
the charge of the outermost layer and the electrolyte concentration and pH. The electrochemical quartz
crystal microbalance (EQCM) has been used to monitor the exchange of ions and solvent with the external
electrolyte during redox switching. At low ionic strength Donnan permselectivity of anions or cations is
apparent and the nature of the ion exclusion from the film is determined by the charge of the topmost layer
and solution pH. At high electrolyte concentration Donnan breakdown is observed and the osmium redox
potential approaches the value for the redox couple in solution. Exchange of anions and water with the
external electrolyte under permselective conditions and salt and water under Donnan breakdown have
been observed upon oxidation of the film at low pH for the PAH-Os terminating layer. Moreover, at high pH
values and with PVS as the terminating layer EQCM mass measurements have shown that cation release
was masked by water exchange.